1. Field of the Invention
The present invention relates in general to an engine, and in particular to a component layout for a marine engine, including an arrangement for the oxygen sensor.
2. Description of Related Art
Internal combustion engines are commonly used to power small watercrafts such as personal watercraft. These watercraft include a hull which defines an engine compartment. Personal watercraft often employ an inline, multi-cylinder, crankcase compression, two-cycle engine. The engine conventionally lies within the engine compartment with the in-line cylinders aligned along a longitudinal axis of the watercraft hull. An output shaft of the engine is coupled to a water propulsion device of the watercraft, such as an impeller.
Generally, the engine of the small watercraft further includes an air intake system, an exhaust system, a fuel supply system, and other components to operate the engine. Air is supplied to the engine from the outside of the hull for use in the combustion process. Typically, air flows through one or more ducts in the hull into the engine compartment, and then through the intake system to the cylinders. An exhaust system communicates with the cylinders of the engine and extends to a discharge that is located near the stem of the watercraft.
Performance of the combustion process is monitored and controlled. An oxygen sensor is provided to the engine to monitor oxygen concentration in the exhaust gases, which is used to control the amount of fuel to be supplied to the combustion process. The oxygen sensor is very sensitive to water, and water that contacts the sensor may deteriorate the sensitivity and/or the durability of the sensor.